The invention relates to avian, vitelline antibodies directed against HIV antigens, methods for their preparation, and their use. These antibodiesxe2x80x94monospecific, polyclonal egg yolk antibodies from SPF chickens (specified pathogen-free chicken)xe2x80x94are suitable in HIV (human immunodeficiency viruses) diagnostics and in the therapeutical use on HIV-positive patients in the symptom-free stage, and where symptoms of ARC (AIDS-related complex) or AIDS (acquired immunodeficiency syndrome) are present.
Since the end of the last century it is well-known that considerable amounts of antibodies (Ab) may be accumulated in chicken egg yolk (Klemperer F., Arch. exptl. Pathol. Pharmakol. 31 (1893) 356-382). Over the last ten years, there were massively increasing efforts to recover antibodies from bird eggs and utilize them for medical purposes. In contrast to other methods, the antibody accumulation and recovery via bird""s egg is a bloodless method, since blood withdrawal is not required for Ab recovery (Schade, R. and A Hlinak: Mh. Vet.-Med. 48 (1993) 91-98, Gustav Fischer Verlag, Jena).
The well-known methods comprise immunization of chickens with an antigen and recovery of the antibodies (IgY, yolk antibodies) from the eggs/egg yolk (US=US patent, GB=British patent, DD=East German application, DE=German unexamined application (OS)/patent specification (PS), EP=European patent, WO=PCT(Patent Cooperation Treaty) application: Immunologically reactive preparations (Egg Yolk Antibodies, Polson, A.: DE 29 51 412), Egg Yolk Antibodies (Polson, A.: GB 2,057,451, U.S. Pat. No. 4,357,272), Fowl Egg Antibodies (Polson, A.: U.S. Pat. No. 4,550,019), Specific Chicken Egg Antibodies (Tsuda, K. et al.: EP 503,293), Specific antibody-containing substance from eggs (Tokoro, H.: U.S. Pat. No. 5,080,895, EP 225,254).
Passive immunization of mammals using antibodies recovered from a fowl species has also been described (Stolle, R. and L. R. Beck: DE 35 04 221, U.S. Pat. No. 4,748,018, EP 152,270). Therein, immunizing quantities of an antibody recovered from eggs of a fowl species immunized with the antigen causing the mammal""s disease are administered to the mammal.
Another well-known example is the successful passive immunization against rotavirus infections in mammals using avian, vitelline antibodies (Bartz, C. R. et al., The Journal of Infectious Diseases, Vol. 142, No. 3, 1980, 439-441; Yolken, R. H. et al., Pediatrics (1988) 81 (2) 291-295; Kuroki, M. et al., Veterinary Microbiology, 37 (1993) 135-146); and the passive immunization of mammals using avian antibodies against E. coli (Wiedemann, V. et al., Journal of Veterinary Medicine, Series B (1990) 37 (3), 163-172; ibid., (1991) 38(4), 283-291; Yokoyama, H. et al., Infection and Immunity (1992) 60 (3), 998-1007).
The structural differences between avian and mammal IgG are explained on the basis of the phylogenetic divergence of birds and mammals. Above all, they are apparent from the differences in molecular weights and sedimentation constants: chicken IgG 170,000 or 174,000, human IgG 150,000 daltons (Larsson, A. and J. Sjxc3x6quist, Comp. Immun. Microbiol. infect. Dis., Vol. 13, No. 4, pp 199-201, 1990; Jxc3xcrgens, L.: Reinigung von IgG und IgG-Antikxc3x6rpern aus dem Eidotter, Ph.D. Thesis 1987, Ludwig-Maximilians-Universitxc3xa4t, Munich).
It is also well-known that HIV-infected cells express core antigens on their cell membranes, e.g. p24 antigen (Nishino, Y. et al., Vaccine, 1992, 10 (10) 677-683). An in vitro inhibition of HIV infection using anti-p24 antibodies is described by Gregersen J. P. et al. (J. Med. Virol. 1990, 30(4) (287-293) and Franke, L. et al. (J. Med. Virol. 1992, 37 (2) 137-142). The influence of a high anti-HIV p24 antibody titer on the condition of HIV-positive patients is the subject matter of WO 89/01339 (Cummins, L. M. et al.), and that with the proteins gp41 and p24 of corresponding antibodies is the subject matter of WO 90/09805 (Zolla-Pazner, S. et al.). The assessment of the immunologic defense pattern of a patient is the essence of DD 299 090, according to which the anti-HIV Ab content of the patient after treatment with monoclonal antibodies (mAb) particularly directed against the HIV protein p24 (anti-HIV p24 mAb) is determined using ELISA (Enzyme-Linked Immunosorbent Assay).
The symptoms of ARC and AIDS, respectively, begin with a massive decrease or total disappearance of the anti-p24 antibodies from the serum of HIV-positive patients (Jackson, G. G., The Lancet, Sep. 17, 1988, 647-651; Karpas, A. et al., Proc. Natl. Acad. Sci. USA, Vol. 87, pp 7613-7617, October 1990), whereas patients having a high anti-p24 antibody titer remain symptom-free. Several authors conducted a passive immunization with patients in the ARC and AIDS stages (Karpas, A. et al. 1990, ibid.; Karpas, A. et al., Int. Conf. AIDS, Jun. 6-11, 1993 9 (1), 244, Abstract No. PO-A28-0659; Jackson, G. G., ibid.; Hague, R. et al., Int. Conf. AIDS, Jun. 4-9, 1989 , 5, 328, Abstract No. T.B.P. 246; Lefrere, J. J. et al., a) Int. Conf. AIDS, Jun. 6-11, 1993 9 (1), 246, Abstract No. PO-A28-0667; b) Rev. Fr. Transfus. Hemobiol., May, 34 1994 (3), 199-211; c) Int. Conf. AIDS, Aug. 7-12, 1994 10 (1), 226, Abstract No. PBO335), where plasma from symptom-free patients (up to 500 ml) with high anti-p24 antibody titer was transfused to patients in the ARC and AIDS stages after the viruses in the plasma had been inactivated by heat. Two hours after transfusion, p24 could not be detected in the serum anymore; also, the number of HIV-infected cells was reduced. Patients in the ARC stage showed significant amelioration of the clinical symptoms up to complete absence of symptoms. There was no decrease in the number of T4-helper cells anymore.
To date, survival with absence of symptoms for periods as long as 22 and 35 months has been described. With patients in an advanced stage of AIDS, remission continued for 6 to 22 months, depending on the state of the individual severity level of the disease at the time treatment had begun, with present aviremia and sufficient antibody level. In the ARC stage, the clinical remission continued 22 months beyond the KARPAS study, with present aviremia and stable CD4+ T-cell number (Karpas, A. et al., Int. Conf. AIDS, Jun. 6-11, 1993, 9 (1), 244, Abstract No. PO-A28-0659; Bainbridge, D. et al., Int. Conf. AIDS, Aug. 7-12, 1994, 10 (1), 216, Abstract No. PB 0293).
The invention is based on the object of providing antibodies directed against HIV antigens, which may be administered to HIV-infected patients. The object was accomplished by immunizing chickens with HIV antigens, thereby accumulating anti-HIV antibodies in the egg yolk. Surprisingly, it was found that administering these antibodies in the form of an oral administration of dried egg yolk or as antibody extract after isolation from egg yolk and work-up results in increased antibody serum titer values, and that avian antibodies in mammals are capable of binding the mammal complement.
As a result of the phylogenetic divergence between birds and mammals, fowl species for the production of antibodies against mammal diseases had been excluded, particularly for the reason that chicken protein was foreign to the human immune system and would give rise to allergic reactions when used repeatedly (DE 35 04 221 C2 dated May 19, 1994). According to Gippner-Steppert et al., chicken antibodies xe2x80x94in contrast to mammal antibodiesxe2x80x94would give no reaction with mammal complement factor C1 and mammal Fc-receptors (Gippner-Steppert, C. and M. Jochum: xe2x80x9cProduction and purification of chicken polyclonal anti-peptide antibodies specific for fibrino-elastase-peptide A-alphal-21xe2x80x9d, lecture held during the public annual colloquium of the Surgical-Medical Clinic of the LMU Munich, Feb. 4, 1994).
The antibodies of the invention are novel both as avian antibodies and in their structure. They differ from well-known antibodies in molecular weight, sedimentation constant and isoelectric point.
According to the invention, particularly those antibodies are used which are directed against HIV core antigens. The most important role is assigned to the antibody derived from the core antigen p24, followed by the HIV proteins p17, p7 (9), p12, p66, and p32 (Kageyama, S. et al., Int. Conf. AIDS, Aug. 7-12, 1994, 10 (2), 86, Abstract No. PA 0224).
According to present knowledge, it appears that the anti-p24 antibodies of HIV-positive patients (HIV-1 and HIV-2) protect most effectively from the ARC and AIDS stages to occur. It is not clear as yet, to what extent other antibodies have an additional effect against core antigens.
The antibody titer against core protein p17 decreases earlier than the anti-p24 antibody (Lange, J. M. et al., AIDS, Sep. 1 1987, (3), 155-59).
The anti-core antibodies of the invention, and particularly the antibody against p24 antigen, result in absence of symptoms to a large extent and prolongation of life in ARC stage patients.
For mere logistic reasons, however, only a small circle of affected persons may benefit from the plasma transfusion method of treatment described above.
The avian, vitelline antibodies against core proteins according to the invention offer the advantage that they are produced in large amounts by chickens and transferred to the egg yolk. According to the invention, the antibodies are administered parenterally in a highly purified form, but also on the oral route as dry egg yolk or antibody extract, because they are thermally stable and acid-resistant to a high extent. With the solution of the invention, a new kind of food is offered: the chicken""s egg containing anti-HIV antibodies, wherein the antibodies are accumulated in the egg yolk in particular, but not exclusively.
In particular, core antigens, preferably p24 and p17 are suitable as HIV antigens. Using SPF chickens, they result in the corresponding SPF chicken polyclonal antibodies according to the invention.
The method of the invention for producing avian, vitelline antibodies directed against HIV antigens comprises immunization of chickens with HIV antibodies, particularly core antigens, preferably the core proteins p24 and/or p17, thereby accumulating the antibodies in the egg and egg yolk, respectively, and optional isolation therefrom.
The antibodies of the invention may be used in the passive immunization of mammals. They are suited to be administered to HIV-positive patients in order to produce high antibody serum titers.
The isolation of the IgY antibodies of the invention is effected from aqueous yolk solutions according to well-known procedures, using PBS (phosphate-buffered sodium chloride solution) as solvent and subsequent centrifugation, precipitation of immunoglobulins by means of precipitating agents such as polyethylene glycol (PEG), sodium, dextran or ammonium sulfate and/or chromatographic purification such as gel filtration or ion exchange (Schade, R. and A. Hlinak: Mh. Vet.-Med. 48, 1993, p. 95, Gustav Fischer Verlag, Jena).